1. Field of the Invention
The present invention relates to an image display apparatus for displaying an image by exciting a phosphor that is provided on one substrate and emitting a light thereof by means of an electron emitted from an electron emission element that is provided on another substrate facing the one substrate.
2. Description of the Related Art
In recent years, a flat image display apparatus such as a field emission display (FED) and an image display apparatus provided with a surface-conduction electron emission element (SED) has been known.
An example of the inner structures of conventional FED and SED is shown in FIG. 6. The conventional FED and SED have a vacuum package 4, in which peripheries of a face plate 2 and a rear plate (corresponding to “an electron source substrate” of the present invention) 3 that are arranged oppositely via a spacer 1 are joined with each other by a side wall of a rectangular-frame shape.
Then, on the inner surface of the face plate 2, a plurality of light emitting members (phosphors) and a metal back 6 to cover this are formed. On the other hand, on the inner surface of the rear plate 3, an electron emission element 7 for emitting en electron to excite a light emitting member that is formed on the face plate 2 and emit a light thereof is formed in response to each light emitting member. A voltage higher than that of the electron emission element 7 by several kV is applied to the light emitting member, and an electron (an electron beam) discharged from each electron emission element 7 is accelerated by this electric field. Accelerated electrons are irradiated to the corresponding light emitting member to excite the light emitting member and emit the light thereof.
As described above, in the FED and the SED, in order to accelerate the electron, a high voltage is applied between the adjacent face plate and rear plate, so that this frequently involves a problem about discharge. If discharge is caused, large current flows through the discharge parts and this gives a serious damage to the electron emission element.
Therefore, in order to solve the above-described problem due to discharge, a soft flash structure has been suggested by Japanese Patent Application Laid-Open No. 2006-120422. According to the soft flash structure, the current flowing upon generation of discharge is limited in such a manner that the metal back to cover the light emitting member on the face plate is electrically divided into small areas and a high resistance is given between respective divided areas.